Introduction: I've
spent a great deal of time looking through various publications and climatic data for
Central/Northern Chile. The data, combined with what is known about regions of the world with similar
meteorological patterns, show that most if not all Copiapoas receive most moisture during their
winter. Yet,
many publications on cactus indicate a summer to fall growing period in cultivation.
I'm sure some grower's
local conditions necessitate employing a summer growing period. But do other growers automatically
assume Copiapoas require a summer growth period? Data indicates the entire area's frequent
coastal fog, which provides moisture for many
Copiapoas, is most prominent during the southern hemisphere's
winter and spring. I'm
skeptical about claims that fog is the primary moisture source for all Copiapoas since some, even in the north,
are not found at elevations where the fog generally occurs. Most of the area's infrequent precipitation
also occurs in winter. And the chance of precipitation can dramatically increase during El Nino periods (abnormally warm coastal
waters), especially in winter. La Nina (abnormally cool coastal
waters) period data is more sketchy, but the results should be an increase in moisture providing fog/mist. Expert opinions on the frequencies
of El Nino vary
anywhere from 3-10 years to 7-30 years.
But it's all a matter of what actually constitutes an El Nino since the water temperatures
frequently fluctuate. The 3-10 year cycle claim is based on periods of slightly warmer water, whereas longer period claims
are tied to significantly warmer water. But what does it take to create a noticeable change in rainfall? It would be interesting to know
what transpired in the area this last, significant El Nino, in 1997-98.
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